Field of the Invention
The present invention relates to body tissue-derived Pluripotent stem cells.
Background Art
Planarians and newts can regenerate their entire bodies even after their bodies have been cut. Such high regenerative capacity depends on the presence of pluripotent stem cells existing in the mesenchymal tissues. However, in the case of higher organisms such as humans, the tissue regenerative capacity is far lower than that of those animals. An inner cell cluster (or ICM: inner cell mass) in a mammalian blastocyst is recognized as a collection of pluripotent stem cells that is capable of differentiating into cells of ectodermal, mesodermal, and endodermal cell lineages. However, such pluripotency becomes limited as development proceeds, followed by cell differentiation for specialization resulting in each type of tissue.
In recent years, adult stem cells or tissue stem cells that can contribute to tissue regeneration have been attracting attention. However, it has remained unknown whether or not pluripotent stem cells are present in mature mammalian bodies, as in the case of planarians or newts.
Bone marrow stromal cell (MSC) fractions having the ability to differentiate into bone, cartilage, adipocytes, neuronal cells, skeletal muscles, and the like have been reported as cells obtained from an adult having differentiation potency (see Non-Patent Documents 1 and 2). However, bone marrow stromal cells (MSCs) are comprised of various kinds of cell populations. The differentiation potency of MSC population is varied, but the main body thereof is not clearly understood. Furthermore, it requires stimulation with a specific compound, gene transfer, or the like for differentiation into specific cells. Specifically, there is a need to construct a system for inducing differentiation.
Furthermore, iPS cells (induced pluripotent stem cells) (see Patent document 1, Patent document 2, Non-patent document 3, and the like) have been reported as adult-derived pluripotent stem cells. However, establishment of iPS cells requires an induction operation using a specific substance, such as introduction of a specific gene into a dermal fibroblast fraction (dermal fibroblast) that is a mesenchymal cell population or introduction of a specific compound into somatic cells.    Patent document 1 JP Patent No. 4183742    Patent document 2 JP Patent Publication (Kokai) No. 2008-307007 A    Non-patent document 1 M. DEZAWA et al., The Journal of Clinical Investigation, 113, 12, pp. 1701-1710, (2004)    Non-patent document 2 M. DEZAWA et al., SCIENCE, 2005 Jul. 8, 309, pp. 314-317, (2005)    Non-patent document 3 Okita K. et al. SCIENCE, 2008 Nov. 7, 322 (5903), pp. 949-953